Motors for HAW machines typically require a high speed range in order to drive both the wash cycle and the spin cycle of a washing machine. In particular, such motors usually operate over a wide speed range of approximately 30 to 1. During the wash cycle, the motor operates at a low speed typically in the range of 400-800 rpms with high torque. During the spin cycle, the motor operates at a high speed, typically in the range of 12,000-18,000 rpms with low torque. Many CIMs in HAW machines operate in a wide speed range of 500 rpms-18000 rpms, representing a flux weakening range of 5 or more.
In the range of motors with stators having a diameter equal to or less than 6.3 inches, several combinations of poles and slots are used to accomplish the necessary field weakening range required for HAW machines. For example, such motors have been implemented as 2 pole, 24 slot CIMs.
Although 2P/24S CIMs may be designed to meet the wide speed range requirements of HAW machines, the 2P/24S CIMs are larger than desired, having higher stator end turns and increased material costs. There is a need for a wide speed CIM or BPM motor having a smaller configuration to accommodate lower stator end turns and to provide reduced material costs in a more compact motor design.
In industrial range motors having stator outside diameters in the range of 5.5 inches to 6.3 inches, 4 pole, 36 slot motors have been used. However, such industrial range motors have not been known to be used for flux weakening ranges of about 5 or more. In addition, such motors have been observed to ID/minimum OD ratios (e.g., inside diameter/diameter across flats) to be less than 0.63. For various reasons, such motors have not been employed in HAW machines as unsuitable to meet the drive, weight and size requirements.